1. Field of the Invention
The present invention relates to an inverted strut damper.
2. Discussion of the Background Art
Conventionally, an inverted strut damper is a structure having a damper tube fitted movably upwards and downwards through upper and lower oil seals and upper and lower bearings in an outer cylinder, for lubricating the upper and the lower oil seals and the upper and lower bearings with oil.
In Japanese Patent Application No. 8-227211, the applicant of the present invention has previously proposed a technique for improving lubrication of the upper bearings and the upper oil seals by filling a lubricating chamber storing oil to the full by putting a hollow elastic substance in the lubricating chamber. This technique will be explained below with reference to a drawing of this application.
FIG. 7, labeled "PRIOR ART", is an enlarged diagram of an upper section of an outer cylinder for a conventional inverted strut damper. This diagram shows that an upper oil seal 102 is provided on the top end of an inner plane of an erected outer cylinder 101 of an inverted strut damper 100. Upper bearings 103 are fitted beneath this upper oil seal 102, lower bearings 104 are fitted in the middle of the inner plane of the outer cylinder 101, a lower oil seal 105 is fitted beneath the lower bearings 104. A damper tube 106 is inserted movably upwards and downwards between these upper and lower oil seals 102 and 105 and upper and lower bearings 103 and 104, and a space formed by encircling it with the upper and lower oil seals 102 and 105, and the outer cylinder 101. The damper tube 106 is used as a lubricating chamber 107 for lubricating the upper and lower oil seals 102 and 105 and the upper and lower bearings 103 and 104.
A reference number 108 denotes a porous elastic substance and 109 denotes a distance collar.
The volume of the oil within the lubricating chamber 107 gradually decreases along with its use over a long period of time, so that the upper oil seal 102 and the upper bearings 103 lose their oil impregnation. However, by the upward and downward movement of the damper tube 106, the oil adhered to the outer plane of the damper tube 106 is supplied to the upper oil seal 102 and the upper bearings 103 to lubricate the upper oil seal 102 and the upper bearings 103 without problem.
Although it is always possible to lubricate the upper oil seal 102 and the upper bearings 103 as described above, a further improvement in lubrication is desired under severer lubricating conditions required for the bearings and the oil seals due to the increase in piston speed along with the higher speed of vehicles that occurred in recent years.
The lower bearings 104 and the lower oil seal 105 can be fitted in a simple manner since they can be inserted without pressuring. However, since there is a long distance of the same diameter of the outer cylinder 101 from its upper end to the positions where the lower bearings 104 and the lower oil seal 105 are fitted, a further improvement in their fitting by shortening this distance is also desired.